U.S. patent number 4,519,590 [Application Number 06/455,695] was granted by the patent office on 1985-05-28 for axle clamp for filament reinforced synthetic material leaf springs.
This patent grant is currently assigned to Ford Motor Company. Invention is credited to Wayne E. Wells.
United States Patent |
4,519,590 |
Wells |
May 28, 1985 |
Axle clamp for filament reinforced synthetic material leaf
springs
Abstract
An improved axle clamp is required, particularly for use with
composite material leaf springs, to securely fix the position of
the leaf spring relative to the axle or other wheel carrying member
such as in the suspension system of an automotive vehicle. The
present invention provides an axle clamp comprising a clamp base
(1) and a wedge insert (2). The clamp base provides a platform
portion (3) and substantially parallel side walls (4A, 4B)
extending from the platform portion to form a channel adapted to
receive the wedge insert. The inner surface of at least one side
wall of the clamp base provides a channel-widening concavity (5A,
5B). The wedge insert has a platform portion (7) and substantially
parallel side walls (9A, 9B) extending from the platform portion
forming an inner channel adapted to jacket a mid-portion of the
leaf spring (10). The outer surface of at least one side wall of
the wedge insert provides a convexity adapted to engage and
substantially fill the channel-widening concavity of the clamp
base. According to one embodiment, an axle clamp assembly comprises
the clamp base and wedge insert and further comprises a clamp plate
(12) positioned over the leaf spring opposite the clamp base and
adapted to be attached thereto to hold the leaf spring securely
between them. Optionally, a resilient pad (11) is provided mediate
the leaf spring and the clamp plate.
Inventors: |
Wells; Wayne E. (Farmington
Hills, MI) |
Assignee: |
Ford Motor Company (Dearborn,
MI)
|
Family
ID: |
23809898 |
Appl.
No.: |
06/455,695 |
Filed: |
January 5, 1983 |
Current U.S.
Class: |
267/52; 403/226;
267/149 |
Current CPC
Class: |
B60G
11/113 (20130101); B60G 11/40 (20130101); F16F
1/3683 (20130101); B60G 2204/4306 (20130101); B60G
2200/31 (20130101); Y10T 403/456 (20150115) |
Current International
Class: |
B60G
11/40 (20060101); B60G 11/02 (20060101); B60G
11/32 (20060101); B60G 11/113 (20060101); F16F
1/36 (20060101); F16F 1/368 (20060101); F16F
001/30 () |
Field of
Search: |
;267/36R,38,40,42,43,44,47,49,51,52,53,148,149
;403/203,221,222,226,227,390,392 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Halvosa; George E. A.
Assistant Examiner: Diefendorf; Richard R.
Attorney, Agent or Firm: McDermott; Peter D. May; Roger
L.
Claims
What is claimed is:
1. An axle clamp adapted to hold a synthetic material leaf spring
in position relative to an axle, which leaf spring has upper, lower
and side surfaces, which axle clamp comprises a rigid clamp base
and a resilient wedge insert, said clamp base comprising a platform
portion and two substantially parallel side walls extending from
said platform portion to form a channel adapted to receive said
wedge insert, the inner surface of at least one said side wall
providing a channel-widening concavity, and said wedge insert
comprising a wedge insert platform portion and two substantially
parallel wedge insert side walls extending from said wedge insert
platform portion to form an inner channel adapted to have planar
surface contact with said side surfaces of said leaf spring at a
mid-portion of said leaf spring for frictional engagement thereof
to provide longitudinal positioning of said leaf spring, the outer
surface of at least one said wedge insert side wall providing a
convexity adapted to engage and substantially fill said
channel-widening concavity; and means for clamping said leaf spring
in said clamp base.
2. The axle clamp of claim 1, wherein said wedge insert comprises a
material selected from the group consisting of natural rubber,
synthetic rubber and the like.
3. The axle clamp of claim 1, wherein said wedge insert comprises
cloth fabric-reinforced synthetic rubber.
4. The axle clamp of claim 1, wherein said wedge insert comprises
urethane synthetic rubber.
5. An axle clamp assembly adapted to secure a synthetic material
leaf spring in position in a suspension system, which leaf spring
has upper, lower and side surfaces, said axle clamp assembly
comprising:
a rigid clamp base comprising a platform portion and two
substantially parallel side walls extending from said platform
portion to form a channel, the inner surface of at least one of
said side walls providing a channel-widening concavity;
a resilient wedge insert positioned within said channel, comprising
a wedge insert platform portion positioned substantially parallel
to and adjacent to said clamp base platform portion, and two
substantially parallel side walls extending from said wedge insert
platform portion to form an inner channel adapted to have planar
surface contact with said side surfaces of said leaf spring at a
mid-portion of said leaf spring for frictional engagement thereof
to provide longitudinal positioning of said leaf spring, the outer
surface of at least one said wedge insert side wall providing a
convexity substantially filling said channel-widening
concavity;
the mid-portion of said leaf spring being jacketed by said wedge
insert; and
a clamp plate attached to said clamp base, said clamp plate and
clamp base together holding said leaf spring between them.
6. The axle clamp assembly of claim 5 further comprising a
resilient upper pad mediate said leaf spring and said clamp
plate.
7. The axle clamp assembly of claim 5, wherein said wedge insert
comprises a material selected from the group consisting of natural
rubber, synthetic rubber and the like.
8. The axle clamp assembly of claim 5, wherein said wedge insert
comprises cloth fabric-reinforced synthetic rubber.
9. An axle clamp assembly adapted to secure a synthetic material
leaf spring in position in a suspension system, said axle clamp
assembly comprising:
a leaf spring having upper, lower and side surfaces;
a rigid clamp base comprising a platform and two substantially
parallel side walls extending substantially perpendicularly from
opposite edges of said platform portion to form a channel, the
inner surface of each said side wall providing a channel-widening
concavity which is substantially symmetrical, through a plane
bisecting said channel longitudinally, to the channel-widening
concavity of the other side wall of said clamp base;
a resilient wedge insert positioned within said channel comprising
a wedge insert platform portion positioned substantially parallel
to and adjacent to said clamp base platform portion, and two
substantially parallel side walls extending substantially
perpendicularly from said wedge insert platform portion to form an
inner channel adapted to have planar surface contact with said side
surfaces of said leaf spring at a mid-portion of said leaf spring
for frictional engagement thereof to provide longitudinal
positioning of said leaf spring, the outer surface of each said
wedge insert side wall providing a convexity substantially filling
said channel-widening concavity of the corresponding clamp base
side wall;
the mid-portion of said leaf spring being jacketed by said wedge
insert; and
a clamp plate attached to said clamp base, said clamp plate and
clamp base together holding said leaf spring between them.
10. The axle clamp assembly of claim 9 further comprising a
resilient upper pad mediate said leaf spring and said clamp plate.
Description
TECHNICAL FIELD
This invention relates to a novel axle clamp adapted to secure a
filament reinforced synthetic material leaf spring on an axle
without damage or dislocation of the reinforcing filaments or resin
matrix of the leaf spring. The axle clamp of the invention
accurately and securely fixes the position of the filament
reinforced synthetic material leaf spring relative the axle.
BACKGROUND ART
Composite material leaf springs are known, which springs typically
comprise a filler material, for example glass roving or other
filamentary solids, in an organic solid such as thermoplastic or
thermosetting plastic. Such springs are shown, for example, in U.S.
Pat. Nos. 2,600,843; 2,829,881 and 3,142,598. Known methods of
making composite material leaf springs include, for example,
filament winding methods, compression molding methods and
pultrusion methods.
In the past, composite material leaf springs have been used in
automotive vehicle suspension systems with associated hardware to
accurately position and hold the spring. Such spring clamping
hardware has been fashioned after hardware previously known for use
in conjunction with metal leaf springs. In a typical arrangement,
the spring is positioned between a clamping plate on one side and
the axle or other wheel carrying member on the other side. Often, a
second clamping plate or the like is positioned between the spring
and the axle to act as a spring seat. Bolts or the like, for
example U-bolts, are used to clamp the clamping plate and spring to
the axle. An abrasion resistant pad can be used between the spring
and the clamping plate and/or between the spring and the axle (or
spring seat). Exemplary clamping hardware for a composite material
leaf spring is seen, for example, in U.S. Pat. Nos. 3,968,958;
3,586,307 and 3,541,605.
Known leaf spring clamping hardware has been found inadequate in
certain respects for use in conjunction with composite material
leaf springs. Specifically, such spring clamping hardware has been
found inadequate to hold the spring in a fixed position relative
the axle under conditions experienced in ordinary use. More
specifically, known spring clamping hardware has failed in ordinary
use to prevent longitudinal movement of the spring, that is,
movement of the spring in a direction along its longitudinal axis
(which typically is transverse to the longitudinal axis of the
axle). While the longitudinal position of the spring could be
adequately fixed by providing a hole through the composite material
of the leaf spring and bolting the spring to the spring clamping
hardware, this presents several disadvantages. Providing the bolt
hole in the leaf spring requires additional fabrication time and
introduces additional complexity and cost. In addition, the bolt
hole significantly weakens the composite material spring, and so
the spring must be made larger, heavier and more costly.
Movement of the composite material leaf spring relative the axle or
other wheel carrying member in a direction along the longitudinal
axis of the leaf spring changes the pivot point of the leaf spring
against the axle. Consequently, the spring rate is altered and the
spring fails to perform according to design. Moreover, upon flexure
of the spring, the compressive and tensile stresses are improperly
distributed, which can lead to increased material fatigue and
decreased spring life. Moreover, if excessive, such movement can
lead to damage to the vehicle powertrain.
A composite material leaf spring suitable for use on an automotive
vehicle and an axle clamp for use with same is disclosed in
commonly assigned U.S. patent application Ser. No. 405,961 filed
June 25, 1982. The composite material leaf spring comprises a
position-setting concavity in its surface and the axle clamp
comprises a corresponding position-setting convexity. Together, the
position-setting concavity and the position-setting convexity
accurately and securely fix the position of the composite spring
relative the axle clamp and, indirectly, relative the axle. In one
embodiment, a resilient sheet is positioned mediate the clamping
plate and the leaf spring other than at the area of engagement of
the position-setting concavity by the clamping plate channel
convexity, and a resilient spring seat pad is positioned mediate
the leaf spring and the axle or more typically mediate the leaf
spring and a spring seat.
It is an object of the present invention to provide an axle clamp
which secures a filament reinforced composite material leaf spring
in position relative the axle. More particularly, it is an object
of the invention to provide an axle clamp which in ordinary use
substantially prevents longitudinal movement of the leaf spring,
that is, movement of the spring in a direction along its
longitudinal axis. Further, it is a particular object of the
invention to provide an axle clamp which does not require either
damage or dislocation of either the reinforcing filaments or the
resin matrix of the leaf spring and, specifically, which does not
require any hole(s) through the leaf spring or concavities in the
surface of the leaf spring or other complexities in the shape of
the leaf spring.
DISCLOSURE OF THE INVENTION
This invention provides an axle clamp adapted to hold a synthetic
material leaf spring in position relative an axle, which axle clamp
comprises a rigid clamp base and a resilient wedge insert. The
clamp base comprises a platform portion and two substantially
parallel side walls extending from the platform portion to form a
channel adapted to receive a wedge insert. The inner surface of at
least one of the side walls provides a channel-widening concavity.
The wedge insert comprises a platform portion and two substantially
parallel side walls extending from the wedge insert platform
portion to form an inner channel adapted to jacket a mid-portion of
a leaf-spring. The outer surface of at least one side wall of the
wedge insert provides a convexity corresponding to the aforesaid
channel-widening concavity of the clamp base, which convexity is
adapted to engage and substantially fill that corresponding
channel-widening concavity.
The axle clamp of the present invention is seen to be particularly
advantageous in view of its ability to fix or secure the position
of a leaf spring, particularly a filament reinforced composite
material leaf spring, without damaging either the reinforcing
filaments or the resin matrix of the leaf spring. It is
particularly advantageous that the axle clamp provides such
position-fixing function without being bolted to the leaf spring or
otherwise positively attached to it. This advantage presents a
significant advance in the art since it has been found that the
presence of bolt holes and like interruptions and dislocations in
the filament reinforced synthetic material of composite material
leaf springs can significantly reduce the strength, structural
integrity and durability of the leaf spring.
The channel-widening concavity of the clamp base portion of the
axle clamp functions together with the convexity provided by the
outer surface of the wedge insert side wall to prevent movement of
the leaf spring relative to the axle, particularly in a direction
along the longitudinal axis of the leaf spring. Preferably the two
side walls of the clamp base provide symmetrical and oppositely
disposed channel-widening concavities. Preferably the depth of the
concavity in the side wall of the clamp base is uniform in a
direction normal to the platform portion of the clamp base. Axle
clamp embodiments of the invention comprising such preferred
aspects have been found to function quite satisfactorily in use in
the suspension system of an automotive passenger vehicle and
involve relative ease of manufacture and assembly.
According to one most preferred embodiment of the invention
described further below, an axle clamp adapted to secure a
synthetic material leaf spring in position in a suspension system
comprises:
A. a rigid clamp base comprising a platform portion and two
substantially parallel side walls extending substantially
perpendicularly from opposite edges of the platform portion to form
a channel, the inner surface of each side wall providing a
channel-widening concavity which is substantially symmetrical,
through a plane which bisects the channel longitudinally, to the
channel-widening concavity of the other side wall of the clamp
base;
B. a resilient wedge insert positioned within the aforesaid
channel, comprising a wedge insert platform portion positioned
substantially parallel to and adjacent to the clamp base platform
portion, and two substantially parallel side walls extending
substantially perpendicularly from the wedge insert platform
portion to form an inner channel adapted to jacket a mid-portion of
the leaf spring, the outer surface of each wedge insert side wall
providing a convexity substantially filling the channel-widening
concavity of the corresponding clamp base side wall;
C. a leaf spring, the mid-portion of which is jacketed by the wedge
insert, that is, the mid-portion of which is positioned within the
aforesaid inner channel formed by the wedge insert; and
D. a clamp plate attached to the clamp base, which clamp plate and
clamp base together hold the leaf spring between them.
The present invention provides an effective and inexpensive
solution to the problems described above associated with the use of
known composite material leaf springs. By preventing movement of
the leaf spring relative to the axle in a direction along the
longitudinal axis of the leaf spring, the proper pivot point is
maintained for the leaf spring against the axle (or against a
spring seat mediate the axle and the leaf spring). Consequently,
the spring rate is not altered and the spring performs more
consistantly according to design. Thus, upon flexure of the spring,
the compressive and tensile stresses are more properly distributed,
thus avoiding material fatigue which otherwise could decrease the
useful life of the spring. One most significant advantage of the
invention is that it does not require a bolt hole or the like
attachment means at the mid-portion of the leaf spring to
facilitate attachment of the leaf spring to the axle clamp. Thus,
additional fabrication time, complexity and cost required to
provide such attachment means is avoided. In addition, absent such
bolt hole, a spring of a given size will be stronger and more
resilient. Accordingly leaf springs for use with the axle clamp of
the present invention can be designed smaller and of lighter weight
for a given application. Reduced material costs and reduction in
weight are highly significant advantages in applications such as
automotive vehicle suspension, for which the present invention is
especially well suited.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of an axle clamp according to a
preferred embodiment of the present invention.
FIG. 2 is an exploded view of an assembly according to a preferred
embodiment of the present invention, which assembly incorporates
the axle clamp of FIG. 1.
FIG. 3 is an elevation in partial cross-section of the assembly of
FIG. 2 taken through line A--A, shown mounted to an axle using
appropriate additional hardware.
DETAILED DESCRIPTION OF THE INVENTION
Other features and advantages of this invention will become more
apparent from the following, detailed description thereof and from
the drawings illustrating the preferred embodiment and best mode of
carrying out this invention.
Referring now to the drawings, FIG. 1 shows an axle clamp according
to a preferred embodiment of the invention comprising a clamp base
1 and a wedge insert 2. The clamp base has a platform portion 3 and
side walls 4A and 4B extending from the platform portion to form
therewith a channel adapted to receive the wedge insert. Since
composite material leaf springs typically are of rectangular
cross-section, the side walls of the clamp base will typically be
substantially perpendicular to the platform portion. The inner
surface of each side wall provides a channel-widening concavity 5A,
5B That is, the channel-side surface of each side of the clamp base
wall provides a concave region. The clamp base further provides
bolt-holes 6A, 6B 6C 6D (6D not shown) to facilitate assembly of
the axle clamp and attachment thereof to the axle or spring seat.
The wedge insert 2 has a platform portion 7 and substantially
parallel side walls 8A and 8B extending from the platform portion
to form therewith an inner channel adapted to jacket a mid-portion
of the leaf spring. The outer surface of each side wall of the
wedge insert provides a convexity 9A and 9B each being adapted to
engage and substantially fill the corresponding channel-widening
concavity of the clamp base. That is, each side wall of the wedge
insert provides a convex portion or region which matches and is
adapted to mate with the channel-widening concave region of the
adjacent side wall of the clamp base. Of course, for flexibility of
design or other reasons the clamp base side walls can provide
multiple position-fixing concavities and the wedge insert can
provide corresponding convexities for one or more but less than all
of those concavities.
As aforesaid, the wedge insert is adapted to receive and jacket a
mid-portion of the leaf spring. That is, the surface of the inner
channel formed by the wedge insert is contoured to lay closely
against the corresponding surface of the leaf spring. Typically, a
composite material leaf spring will provide an axle attachment
region, a central portion of substantially constant-width. The leaf
spring is generally not, however, of constant-width along its
entire length, but rather becomes wider toward each end before
again becoming narrow at each eye of the leaf spring. According to
a preferred embodiment of the present invention, the axle clamp
extends over a sufficient portion of the leaf spring to jacket not
only the constant-width central portion of the leaf spring but also
some of the wider portion of the leaf spring on either side
thereof. According to this embodiment, the wedge insert is
fashioned such that the contour of its inner channel corresponds to
the contour of the entire portion of the leaf spring which it
jackets. That is, the inner channel becomes wider at each end
corresponding to the widening of the leaf spring.
This can be seen most clearly in FIG. 2 showing an axle clamp
assembly according to a preferred embodiment of the invention. In
leaf spring 10 (the ends of which are broken away) lines 20 and 20A
indicate the boundry between the central constant-width portion of
the leaf spring and the widening portion on either side thereof.
Correspondingly, lines 21 and 21A in the inner channel formed by
the wedge insert are the boundry between the central portion of the
inner channel adapted to jacket the central constant-width portion
of the leaf spring and the portions of the inner channel on either
side thereof, each of which is adapted to jacket part of the
widening portion of the leaf spring. It will be readily understood
from the present disclosure that any longitudinal movement of the
leaf spring relative to the axle clamp of the invention would
produce a wedge effect. That is, any such longitudinal movement of
the leaf spring would act to force a wider portion of the leaf
spring into one end of the inner channel of the wedge insert.
Obviously, any such longitudinal movement would be effectively
prevented by such wedge effect.
The assembly of FIGS. 2 and 3 comprises the clamp base and wedge
insert described above together with a composite material leaf
spring 10 (the ends of which are broken away), a resilient upper
pad 11 and a clamp plate 12. The resilient pad is adapted to be
positioned between the leaf spring and the clamp plate. Also shown
in FIG. 3 for purposes of illustrating an exemplary application of
the present invention are axle 13, spring seat 14 and attachment
means for securing the axle clamp assembly to the axle and spring
seat. The attachment means comprises a pair of U-bolts 15A and 15B
which extend around the axle and through bolt holes in the axle
clamp assembly. The U-bolts are held by four fastening nuts, of
which two nuts 16A and 16D are shown.
The channel-widening concavity of the clamp base and the
corresponding convexity of the wedge insert need not have any
particular configuration or dimensions. A concavity of any
configuration and dimensions is suitable, which upon engagement
thereof by the corresponding wedge insert convexity substantially
secures the composite material leaf spring against movement
relative to the axle in the direction along the longitudinal axis
of the leaf spring. In this regard, the preferred configuration is
that shown in FIGS. 1-3, wherein one concavity is provided in each
side wall of the clamp base, the concavities being preferably
substantially symmetrical through a plane (perpendicular to the
platform portion) bisecting the channel longitudinally. Preferably
each such concavity is such that it gradually and continuously
widens in a direction along the longitudinal axis of the channel to
the longitudinal mid-point of the channel and thereafter gradually
and continuously narrows to its original width, being at each point
preferably of uniform depth over the entire height of the side
wall. Suitable alternative configurations will be apparent to the
skilled of the art in view of the present disclosure. In general, a
suitable configuration will depend, in part, upon the application
to which the axle clamp assembly is to be put and, more
particularly, upon the stress likely to be encountered by the leaf
spring in a direction along the longitudinal axis of the leaf
spring. In general, it will be within the skill of those of average
skill in the art, in view of the present disclosure, to provide an
axle clamp according to the present invention having a clamp base
and wedge insert configuration suitable to substantially fix the
leaf spring in position relative to the axle.
The axle clamp of the present invention is suitable for use in
conjunction with leaf springs fabricated of metal but is
particularly advantageous for use with composite material leaf
springs. Such composite materials typically comprise filler
materials such as, for example, aramid fibers, graphite fibers,
metal fibers, glass roving or other filamentary solids and/or
non-filamentary solids. Glass roving is generally preferred in view
of the physical properties of the resulting leaf spring and in view
of the ease and cost efficiency of manufacturing the leaf springs
by filament winding techniques. The composite material further
comprises an organic solid matrix such as, for example, polyester,
epoxy or other suitable thermoset plastic or a suitable
thermoplastic. As an alternative to filament winding, the leaf
spring can be manufactured by pultrusion methods or by compression
molding or other methods known to the skilled of the art.
Generally, the axle clamp of the present invention can be employed
together with a suitable leaf spring in any application for which
metal or composite material leaf springs are suitable and can be
employed in those applications according to methods well known to
the skilled of the art. Thus, for example, the axle clamp of the
present invention can be used in the suspension system of an
automotive vehicle in conjunction with additional suitable
hardware, substantially as shown in FIG. 3.
Preferably, the clamp base comprises suitable metal, for example,
steel and the channel-widening concavities within the longitudinal
channel of the clamp base can be provided by well known pressing or
stamping operations during the manufacture of the clamp base. In
addition to cast metal, stamped metal and the like, various other
suitable materials and methods of forming the clamp base and
methods of forming the channel-widening concavities thereof will be
apparent to the skilled of the art in view of the present
disclosure. Thus, for example, in certain applications the clamp
base can be formed of suitable thermoset plastic, filament
reinforced thermoset plastic and the like.
In the preferred embodiment shown, the clamp base provides bolt
holes 6A, 6B, 6C and 6D (not shown) adapted to receive U-bolts 15A
and 15B. The U-bolts are adapted to receive fastening nuts 16A, 16D
(shown in FIG. 3) and 16B and 16C (not shown). Alternate methods
and devices of securing the axle clamp assembly (and, hence, the
leaf spring) to the axle or other wheel carrying member, or more
preferably, to a suitable spring seat, such as spring seat 14 shown
in FIG. 3, which is itself mounted to the axle, are known to the
skilled of the art and can be employed in alternate embodiments of
the present invention.
While not wishing to be bound by theory, it is presently understood
that the invention functions by providing a wedge effect between
the wedge insert and the clamp base whereby a high friction
engagement of the inner surface of the wedge insert by the leaf
spring is generated by transmittal of longitudinal forces from the
leaf spring to the axle clamp. Thus, as it is presently understood,
increased loads on the axle serve to increase the wedge effect and
thus to increase the holding capability of the axle clamp. It will
be recognized that the invention provides a significant advance in
the art since the leaf spring is held in position without any
positive attachment between the axle clamp and the leaf spring. No
damage need be done to the leaf spring in the nature of bolt holes
or the like nor any distortion or dislocation of the surface of the
leaf spring to facilitate an attachment between the leaf spring and
the axle clamp.
The thickness and configuration of the wedge insert platform
portion and side walls are not critical, except that the
convexities of the side walls should be designed to engage and
substantially fill the corresponding channel-widening concavities
of the clamp base. The material of the wedge insert, in general,
should be of sufficient thickness and resilience to prevent undue
stress configuration against the surface of the leaf spring, that
is, to disperse pressures transmitted from the clamp base and by
the upper clamp plate. When used in the suspension system of an
automotive vehicle or other similar application, the wedge insert
is preferably sufficiently thick to substantially dampen vibrations
which would otherwise be transmitted from the axle through the leaf
spring to the vehicle chassis. The wedge insert should also be
sufficiently tough to withstand the mechanical working of the clamp
base against the surface of the leaf spring and to protect the leaf
spring against such mechanical working. Suitable materials for the
wedge insert include, for example, natural rubber, suitable
urethanes, suitable neoprenes and the like. Preferably the material
is fabric reinforced, preferably cloth fabic reinforced, since such
reinforced materials have been found to provide excellent tear
resistance, even following prolonged use. Most preferred is cloth
fabric reinforced urethane or neoprene. Natural rubber is less
preferred where the axle clamp assembly is intended for use in the
suspension system of an automotive vehicle or other like
environment in which it may be exposed to oil, gasoline and the
like, in view of the poor resistance of natural rubber to these
elements. Where a urethane is used, preferably it is a hard
urethane and sufficiently tough to withstand prolonged mechanical
working. Other resilient materials suitable to provide the wedge
function of the wedge insert and otherwise suitable for use in the
preferred and alternate environments of the invention will be
apparent to those skilled in the art in view of the present
disclosure.
While the thickness of the resilient upper pad is not critical in
all applications, it should be sufficiently thick to disperse
pressures transmitted from the clamp base and clamp plate to the
composite material leaf spring and to protect the leaf spring
against any edges, etc. presented by the clamp base or by the clamp
plate. When used in the suspension system of an automotive vehicle
or other similar application, the resilient upper pad is preferably
sufficiently thick to aid in substantially dampening vibrations
which otherwise would be transmitted from the axle to the vehicle
chassis. In general, it will be within the ability of those skilled
in the art, in view of the present disclosure, to determine a
suitable configuration and thickness for the resilient upper pad
for use in axle clamp assemblies according to the above-described
or alternate embodiments of the present invention. Suitable
materials for the resilient sheet will be apparent to those skilled
in the art in view of the present disclosure and include, for
example, those materials used for the wedge insert such as natural
rubber and synthetic rubbers, for example neoprenes, urethanes, and
the like.
As noted above FIGS. 2 and 3 illustrate an assembly according to
one embodiment of the present invention, which comprises the clamp
base and wedge insert of FIG. 1 together with leaf spring 10,
resilient pad 11 and clamp plate 12. As seen in FIG. 3, the
assembly is mounted on axle 13 via spring seat 14. It can be seen
that the resilient wedge insert is positioned within the channel
formed by the rigid clamp base. The platform portion of the wedge
insert is positioned substantially parallel and adjacent to the
channel-side surface of the platform portion of the clamp base.
Likewise, the outer surface of the side walls of the wedge insert
are substantially parallel to and adjacent to the channel-side
surface of the corresponding side walls of the clamp base. Thus,
the channel-widening concavity in each clamp base side wall is
substantially filled by a corresponding convexity in the side walls
of the wedge insert. It can be seen that the longitudinal inner
channel formed by the wedge insert jackets a mid-portion of the
leaf spring. The mid-portion of the leaf spring is any longitudinal
portion thereof between the two ends of the leaf spring, which
includes, or at least is proximate the longitudinal mid-point of
the leaf spring. As used herein, in reference to the axle clamp
assembly aspect of the present invention, the mid-portion of the
leaf spring is substantially that portion which is jacketed by the
longitudinal channel of the wedge insert. Typically, such
mid-portion is approximately centered between the two ends of the
leaf spring. The clamp plate is attached to the clamp base such
that together they hold the leaf spring between them. Also included
in this preferred embodiment is an upper resilient pad 11, as
described above, positioned mediate the leaf spring and the clamp
plate.
In FIG. 3, the engagement of the channel-widening concavity in each
side wall of the clamp base by the corresponding convexity of the
outer surface of the side walls of the wedge insert is clearly
seen. It will be recognized from these drawings that the axle clamp
assembly of the present invention effectively and inexpensively
functions to prevent the leaf spring from shifting its position
relative to the axle in a direction along the longitudinal axis of
the leaf spring and also in a direction along the longitudinal axis
of the axle. This latter function may be met in some applications
also by the attachment of the ends of the leaf springs to the
chassis frame.
While the invention has been shown and described in its preferred
embodiment, it will be clear to those skilled in the art that
changes and modifications can be made thereto without departing
from the scope of the invention.
INDUSTRIAL APPLICABILITY
It will be obvious from the foregoing that this invention has
industrial applicability to automotive vehicles and provides an
axle clamp and an axle clamp assembly for the suspension system
thereof, wherein a leaf spring is prevented from shifting its
position relative to the axle or other wheel carrying member in a
direction along the longitudinal axis of the leaf spring. In
addition, the axle clamp and axle clamp assembly of the present
invention have industrial applicability to suspension systems other
than for motor vehicles, for example, for stationary machines and
devices, and further have industrial applicability to uses such as
will be apparent in view of the present disclosure to those skilled
in various related arts.
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